types(runtime-core): add `OnCleanup` parameter type in `this.$watch` (#9371)

packages/dts-test/watch.test-d.ts

@@ -12,10 +12,13 @@ const source = ref('foo')
 const source2 = computed(() => source.value)
 const source3 = () => 1
 
+type OnCleanup = (fn: () => void) => void
+
 // lazy watcher will have consistent types for oldValue.
-watch(source, (value, oldValue) => {
+watch(source, (value, oldValue, onCleanup) => {
   expectType<string>(value)
   expectType<string>(oldValue)
+  expectType<OnCleanup>(onCleanup)
 })
 
 watch([source, source2, source3], (values, oldValues) => {
@@ -92,9 +95,10 @@ defineComponent({
   created() {
     this.$watch(
       () => this.a,
-      (v, ov) => {
+      (v, ov, onCleanup) => {
         expectType<number>(v)
         expectType<number>(ov)
+        expectType<OnCleanup>(onCleanup)
       },
     )
   },

packages/runtime-core/src/apiWatch.ts

@@ -65,7 +65,7 @@ type MapSources<T, Immediate> = {
       : never
 }
 
-type OnCleanup = (cleanupFn: () => void) => void
+export type OnCleanup = (cleanupFn: () => void) => void
 
 export interface WatchOptionsBase extends DebuggerOptions {
   flush?: 'pre' | 'post' | 'sync'

packages/runtime-core/src/componentPublicInstance.ts

@@ -6,6 +6,7 @@ import {
 } from './component'
 import { nextTick, queueJob } from './scheduler'
 import {
+  type OnCleanup,
   type WatchOptions,
   type WatchStopHandle,
   instanceWatch,
@@ -229,8 +230,8 @@ export type ComponentPublicInstance<
   $watch<T extends string | ((...args: any) => any)>(
     source: T,
     cb: T extends (...args: any) => infer R
-      ? (...args: [R, R]) => any
-      : (...args: any) => any,
+      ? (...args: [R, R, OnCleanup]) => any
+      : (...args: [any, any, OnCleanup]) => any,
     options?: WatchOptions,
   ): WatchStopHandle
 } & IfAny<P, P, Omit<P, keyof ShallowUnwrapRef<B>>> &